Bias Voltage Research Articles

The Model and Simulation of Memristor

Memristor is an emerging electronic component, tremendous efforts have been made in the fields of memristor, motivated by its unique resistor switching feature, as well as the good compatibility with the current integrated circuit (IC) technologies. It has been widely accepted that memristor would be a powerful candidate for constructing the brain-like computing hardware system in the next generation of electronics. Even so, there are still challenges in the development of the memristor IC and the calculation system based on it. For an example, the lack of memristor simulation module hinders its automatic design. Herein, we would like to propose a method for simulating the feature of the memristor. Firstly, based on the conductive filament based physical principle of memristor, calculations are conducted to simulate the basic electronic features of memristor. The good fitness confirms the feasibility of the proposed method. Second, the memristor’s resistance switching feature is modelled by Spice, a popular design platform. With the use of Voltage-Controlled Current Source (VCCS) in Spice, a modulus of memristor is established and executed to simulate the switched resistances under different bias voltages. In summary, this work demonstrates the feasibility of the proposed simulating method, it may provide an easy-to-operate way to improve design efficiency of active memristor arrays

Gate-Tunable High-Responsivity Photodiode Based on 2D Ambipolar Semiconductor

Abstract Electrically tunable homojunctions based on ambipolar two-dimensional materials have attracted widespread attention in the field of intelligent vision. These devices exhibit inherent switchable positive and negative photovoltaic properties, that effectively mimic the behavior of human retinal cells. However, the photovoltaic responsivity of most electrically tunable homojunctions remain significantly low due to the weak light absorption, making it challenging to meet the application requirements for high-sensitivity target detection in the field of intelligent vision. Here, we propose a gate-tunable photodiode based on two-dimensional ambipolar WSe2 with an asymmetric gate electrode, achieving high photovoltaic responsivity. By adjusting the gate voltage and keeping bias voltage zero, we can dynamically realize reconfigurable n--p and n--n homojunction states, as well as gate-tunable photovoltaic response characteristics that range from positive to negative. The maximum photovoltaic responsivity of the electrically tunable WSe2 homojunction is approximately 0.4 A/W, which is significantly larger than the previously reported value ~0.1 A/W in homojunction devices. In addition, the responsivity can be further enhanced to approximately 1.0 A/W when the n--p photodiode operates in reverse bias mode, enabling high-sensitivity detection of targets. Our work paves the way for developing gate-tunable photodiodes with high photovoltaic responsivity and advancing high-performance intelligent vision technology.

Boosted Photoelectrochemical Water Oxidation Performance with a Quaternary Heterostructure: CoFe2O4/MWCNT-Doped MIL-100(Fe)/TiO2

Cobalt ferrite (CoFe2O4) combined with multi-walled carbon nanotubes (MWCNTs) is an outstanding material regarding photoelectrochemical water oxidation (PEC-WO) because of its excellent catalytic properties and stability. On the other hand, surface imperfections in CoFe2O4 can cause band bending and surface Fermi level pinning, significantly reducing its PEC conversion efficiency. Heterostructure engineering is essential for achieving increased light-gathering capacity and charge separation efficiency for PEC-WO. In this study, a quaternary heterostructure of CoFe2O4/MWCNT-doped Metal–Organic Framework-100 (Iron), MIL-100(Fe)/Titanium Oxide (TiO2) was synthesized by using a combination of hydrothermal, solvothermal, and “dip and dry” techniques. Characterization results confirmed the formation of a structural network of MIL-100(Fe) on TiO2 surfaces, enhanced by the incorporation of MWCNTs during the hydrothermal reaction. Under 1 sun irradiation, the resultant quaternary heterostructure displayed a photocurrent density (Jph) of 3.70 mA cm−2 under free bias voltage, which is around 3.08 times more than that of pristine TiO2 photoanodes (Jph = 1.20 mA cm−2). This investigation highlights the advantages of the MIL-100(Fe) network in improving the solar PEC-WO performance of TiO2 photoanodes.

Metal‐organic Framework‐derived NiO/ZnO Composites for Photoelectrocatalytic Reduction of Cr(VI)

AbstractNi/Zn‐MOF composites with photoelectrocatalytic (PEC) performance for Cr(VI) reduction were prepared via hydrothermal method and calcinating method. The as‐prepared NiO/ZnO composites exhibited uniform morphology. When being subjected to an external voltage of 0.7 V and irradiated with visible light for 120 min, the NiO/ZnO composite exhibited a Cr (VI) reduction efficiency of almost 100 %, outperforming ZnO and NiO counterparts. The effects of the content of NiO to ZnO and different calcination temperatures on PEC performance were also investigated. Additionally, elimination experiments results indicated that photo‐generated electrons (e−) play a crucial role in the catalytic reduction of Cr(VI). The notable enhancement in the photoelectrocatalytic performance can be credited to the applied bias voltage and the formation of a p‐n heterojunction between NiO and ZnO. Consequently, the NiO/ZnO nanocomposites exhibit significant potential for the PEC reduction of Cr(VI). This capability underscores the promise of NiO/ZnO nanocomposites for applications in the photoelectrocatalytic reduction of Cr(VI) and related environmental remediation processes.

Tuning Self-Polarization of Epitaxial BiFeO3 Thin Films through Interface Effects.

Interface effects and strain engineering have emerged as critical strategies for modulating polarization and internal electric fields in ferroelectric materials, playing a vital role in exploring coupling mechanisms and developing ferroelectric diode devices. In this study, we selected BiFeO3 as a representative ferroelectric material and utilized interface engineering to control its polarization. By precisely manipulating the atomic stacking sequence at the interface, we influenced the electrostatic potential step across the interface, resulting in a bias voltage in the ferroelectric hysteresis loops that defined the ferroelectric state. The introduction of strain and strain gradients through a lattice mismatch between the film and substrate generated a flexoelectric field of approximately 3 MV/m, significantly impacting the internal electric field. Additionally, we successfully modified the Schottky barrier height within BiFeO3 films through the synergy and competition between interfacial and flexoelectric effects. This work expands the potential applications of thin-film flexoelectricity in Schottky diodes, sensors, and memory devices.

Frequency Tunable Film Bulk Acoustic Resonator Integrating PMN‐PT/FSMA Multiferroic Heterostructure for Flexible MEMS

AbstractFrequency tunable flexible piezo resonators exhibit significant potential for technological advances in wearable magnetic field sensing, futuristic wireless telecommunication devices, and flexible micro‐electromechanical systems. This study presents a multifunctional and flexible 0.67Pb(Mg1/3Nb2/3)O3−0.33PbTiO3(PMN‐PT)/Ni50Mn35In15 (Ni‐Mn‐In) multiferroic heterostructure‐based bulk acoustic wave (BAW) resonator fabricated over Kapton substrate. The fundamental resonance frequency (fR = 5.31 GHz) of the resonator is tunable with magnetic and electric fields. A significant change in resonance frequency (ΔfR) of 405 MHz has been achieved with 3.37 Hz nT−1 sensitivity using a direct current (DC) magnetic field of 1200 Oe, attributed to the delta‐E effect. The resonator displays a significant magnetic field tunability of 8.83%. Additionally, a substantial ΔfR of 360 MHz, 36 Hz µV−1 sensitivity and 6.78% tunability is attained with 10 V of DC bias voltage. The impact of magnetic field and DC bias voltage on the acoustic characteristics have been studied by fitting the resonance frequency curves with an equivalent modified Butterworth‐Van Dyke model. The fabricated BAW resonator exhibits outstanding flexibility with no discernible change in fR up to 2000 bending cycles. Such PMN‐PT/Ni‐Mn‐In‐based multiferroic BAW resonators displaying magnetic and electric field tunability are propitious for next‐generation flexible electronics and magnetic field sensors.

Hybrid Terahertz Emitter for Pulse Shaping and Chirality Control

AbstractTerahertz (THz) radiation (0.3 to 30 THz) fills the crucial gap between the microwave and infrared spectral range. THz technology is important for applications ranging from imaging to telecommunication to biosensing, but these applications often require precise control and manipulation of the THz frequency and polarization state, which typically requires modulators external to the THz source. A hybrid THz emitter that overcomes this limitation by integrating two THz emitters into a single device to enable pulse shaping and chirality control of the emitted radiation without any external components is demonstrated. The two sources are a spintronic emitter (SE) and a semiconductor photoconductive antenna (PCA). The two emitters respond independently to external parameters: the PCA is controlled by the applied bias voltage, while the SE is controlled by the applied magnetic field. Moreover, a dual‐wavelength excitation scheme allows for control of the relative time delay between the THz emission from each constituent. These properties of the hybrid emitter enable precise control of the mixing of the two signals to control the frequency, polarization, and chirality of the overall THz radiation. This on‐chip hybrid emitter thus provides a powerful platform for engineered THz radiation with wide‐ranging potential applications.

Dynamically Tunable Terahertz Multiple Plasmon‐Induced Transparency and Slow Light in Planar Metamaterials With Rectangular Interrupted Graphene

ABSTRACTA novel planar monolayer graphene metamaterial structure containing rectangular interrupted graphene is proposed. Dynamically tunable multiple plasmon‐induced transparency (PIT) and slow light are obtained within the terahertz band through destructive interference between continuous dark and interrupted bright modes. Two distinct graphene types function as the optical dark and bright modes, and continuous graphene array is the nonradiative dark mode, whereas interrupted graphene array is the broad linewidth bright mode, respectively. Given the existence of graphene structure in the continuous state, continuous graphene Fermi level is dynamic tuned through the simple use of the bias voltage. Expressions of n‐order coupled mode theory (CMT) are correctly deduced, with CMT fitting theoretical analysis being identical to finite‐difference time‐domain numerical simulation based on dual‐ and triple‐PIT results for n = 3 and n = 4 cases, respectively. The continuous graphene Fermi level increases within 0.7–1.1 eV; the group index of the dual‐PIT system is maintained within 475.1–801.6, while that of the triple‐PIT system is 583.3–886.3. Additionally, the maximal group index is as high as 886.3 at 1.1 eV, indicating that an outstanding slow light device is established. Consequently, these proposed structures and research outcomes can guide the design of multichannel optical filters, excellent slow light devices, and dynamically tunable optical modulators.

Photocurrent Polarity-Switchable Imaging of Single Living Cells by Light-Addressable Electrochemical Sensor.

The light-addressable electrochemical sensor (LAES) is a powerful tool for single-cell imaging due to its label-free and probe-free advantages. In this work, we report a photocurrent polarity-switchable LAES using a single-phase photoelectrode of a BiFeO3 thin film for living cell imaging. The proposed BiFeO3 could show both p- and n-type photocurrent behavior by simply altering the external bias voltage. LAES imaging of the same individual MCF-7 cells was performed in anodic and cathodic modes. Decreases in both photocurrents were observed due to the hindering effect of the adherent cells on local photoinduced Faraday currents. Furthermore, the dynamic photocurrent changes on cells after trypsin treatment were imaged and studied at anode and cathode polarities. Both polarities showed an increase in local photocurrents on cells as the cell-substrate junction weakened, and this change displayed heterogeneous characteristics. This is the first time that LAES cell imaging was achieved in a p-type mode. Meanwhile, our photocurrent polarity-switchable imaging approach overcomes the limitations of conventional photoelectrodes, which have been confined to single-polarity operation. We believe this work has the potential to significantly broaden the application scope of LAES in single-cell visualization and analysis, offering great insights into cellular behavior and function.

Memristor‐Based Reconfigurable True Time Delay Circuit

ABSTRACTA memristor‐controlled CMOS reconfigurable true time delay circuit is introduced in this paper. The delay circuit includes three stages of ‐C all‐pass filter delay elements connected in cascade and memristor‐based tunable DC voltage sources. The memristor value variation changes the DC bias voltage inputs of the delay elements and thus controls the delay time indirectly: The memristor resistance changes in analogue from 10 to 17 k, changing the tunable DC voltage source output from 584‐ to 711‐mV DC voltage and the delay from 269 to 632 ps. The delay circuit can work in a frequency range from 50 MHz to 1.6 GHz with gain ripple smaller than 3 dB. The resolvable delay time step across the delay range is < 8.7 ps, troughing at as low as 0.4 ps. A delay circuit working in the MHz region is also designed to compare the performance with the GHz circuit, and a memristor‐programming circuit is built to change the resistance levels of memristors.

Susceptibility to Low-Frequency Breakdown in Full-Wave Models of Liquid Crystal-Coaxially-Filled Noise-Shielded Analog Phase Shifters

Building on the fully encapsulated architecture of liquid crystal (LC) coaxial phase shifters, which leverages noise-shielding advantages for millimeter-wave wideband reconfigurable applications, this study addresses the less-explored issue of low-frequency breakdown (LFB) susceptibility in modern full-wave solvers. Specifically, it identifies the vulnerability nexus between the tuning states (driven by low-frequency bias voltages) and the constitutive elements of LC-filled coaxial phase shifters—namely, the core line, housing grounding, and radially sandwiched tunable dielectrics—operating at millimeter-wave frequencies (60 GHz WiGig), microwave (1 GHz), and far lower frequency regimes (down to 1 MHz, 1 kHz, and 1 Hz) for long-wavelength or quasi-static conditions, with specialized applications in submarine communications and geophysical exploration. For completeness, the study also investigates the device state prior to LC injection, when the cavity is air-filled. Key computational metrics, such as effective permittivity and characteristic impedance, are analyzed. The results show that at 1 kHz, deviations in effective permittivity exceed four orders of magnitude compared to 1 GHz, while characteristic impedance exhibits deviations of three orders of magnitude. More critically, in the LFB regime, theoretical benchmarks from 1 MHz to 1 kHz and 1 Hz demonstrate an exponential increase in prediction error for both effective permittivity, rising from 16.8% to 1.5 × 104% and 1.5 × 107%, and for characteristic impedance, escalating from 8.1% to 1.15 × 103% and 3.9 × 104%, respectively. Consequently, the prediction error of the differential phase shift, minimal at 60 GHz (0.16%), becomes noticeable at 1 MHz (4.39%), increases sharply to 743.88% at 1 kHz, and escalates dramatically to 2.18 × 1010% at 1 Hz. The findings reveal a pronounced frequency asymmetry in LFB susceptibility for the LC coaxial phase shifter biased at extremely low frequencies.

Comparative Study on the Electrocatalytic Performance of ABO3-Based Hexagonal Perovskite Oxides with Different [AO3] Layers.

To systematically investigate the influence of the number of [AO3] layers in the unit cell of hexagonal perovskite oxide on the oxygen evolution reaction performance, we successfully synthesized the three new hexagonal perovskite oxides 2H-BaCo0.9Ru0.1O3-δ, 6H-BaCo0.9Ru0.1O3-δ, and 10H-BaCo0.9Ru0.1O3-δ with the same element composition but different [BaO3] layers via the sol-gel method. Here, 2H, 6H, and 10H refer to the number of [BaO3] layers contained in the unit cell of the BaCo0.9Ru0.1O3-δ system. Experimentally, 10H-BaCo0.9Ru0.1O3-δ, featuring ten layers of [BaO3], exhibits optimal electrochemical activity among the three oxide catalysts, and in situ Raman results under various bias voltages confirm its ability to maintain a high surface crystal structural stability. Notably, as the number of [BaO3] layers increases, the effective magnetic moments and the valence state of surface Co ions in these three catalysts also increase, with the spin configuration of the surface Co ions being in a high-spin state. More importantly, DFT calculations provide the evolution rules of the p-band center (εp) with the number of [BaO3] layers, predicting the electrochemical performance of the BaCo0.9Ru0.1O3-δ system with different [BaO3] layers. Our experimental results offer a distinctive perspective for the future design, synthesis, and application of hexagonal perovskite oxides in electrocatalysis.

Plasmon-Exciton Strong Coupling in Single-Molecule Junction Electroluminescence.

Single molecules bridging two metallic electrodes can emit light through electroluminescence when subjected to a bias voltage. Typically, light emission in such devices results from transitions between molecular states, although in the presence of light-matter coupling, the emission can result from a transition between hybrid light-matter states. Here, we create single metal-molecule-metal junctions and simultaneously collect conductance and electroluminescence data using a scanning tunneling microscope (STM) equipped with a custom spectrometer. Through experimental analysis and electronic structure calculations, we provide evidence for a molecule-electrode interfacial exciton coupled to a junction cavity plasmon. Importantly, we find that close to resonant transport conditions, the molecular junction functions as a single emitter that is strongly coupled to the junction cavity mode, leading to characteristic Rabi splitting of the emission spectrum and providing the first example of an electroluminescence-driven single-molecule system in the regime of strong light-matter coupling.

Enhancing room temperature thermoelectric efficiency in zigzag phosphorene nanoribbon junctions through Quasi-Flat impurity bands

Abstract In this study, a novel approach has been utilized to Please specify the corresponding author.explore the room temperature thermoelectric properties of zigzag phosphorene nanoribbon-based monolayer-bilayer-monolayer junctions. To achieve thermoelectric properties at room temperature, a quasi-flat energy band with limited width is required. It has been demonstrated, for the first time, that such bands can be observed by considering a junction of the monolayer and bilayer phosphorene nanoribbons. By adjusting the ribbon widths, quasi-flat bands are produced. This geometrical problem is solved using analytical calculations for a general system and applied to phosphorene. We show that the edge states of phosphorene resemble a one-dimensional tight-binding system, with a close agreement between their results. Using the introduced approach, we calculate the electronic energy band structure of the specified system. Initially, we demonstrate that the formation of zigzag monolayer-bilayer-monolayer junctions can lead to the emergence of quasi-flat impurity bands within the energy bandgap. Furthermore, we show that utilizing these structures at room temperature, across a wide range of lead temperature differences, results in significant output electrical power and improved thermoelectric efficiency. The electrical power and thermoelectric efficiency are examined as functions of applied bias voltage and average chemical potential. Additionally, we explore how the output electrical power, thermoelectric efficiency, and efficiency at maximum power vary with the temperature difference between the leads at the ends of the structure.

Pulsed beam monitoring for electron FLASH.

Safe implementation and translation of FLASH radiotherapy to the clinic requirehs development of beam monitoring devices capable of high temporal resolution with wide dynamic ranges. Ideal detectors should be able to monitor LINAC pulses, withstand high doses and dose rates, and provide information about the beam output, energy/range, and profile. Two novel detectors have been designed and tested for ultra-high dose-rate (UHDR) monitoring: a multilayer nano-structured 3-layer high-energy-current (HEC3) detector, and a segmented large area, 4-section flat (S4) detector with the goal of exploring their properties for a future combined design. A Novalis-TX LINAC was converted to produce a 10 MeV electron-FLASH beam. Pulses were monitored using both HEC3 and S4 detectors. The HEC3 detector structure consisted of three electrode layers separated by a nanoporous aerogel (Aero): Al(50µm)-Aero(100µm)-Ta(10µm)-Aero(100µm)-Al(50µm). The S4 structure was comprised of three layers: Cu(100nm)-air(1mm)-Al(100nm) with contact potential for charge collection. Both detectors are self-powered as they do not require an external voltage bias for charge collection. The beam was also characterized using a photodiode, Gafchromic EBT-XD Film, OSLDs, and an Advanced Markus Chamber. The electron-FLASH beam displayed a Gaussian-like profile with 15cm FWHM at isocenter. Electron-FLASH dose rates up to an average of 260Gy/s were measured on the surface of a solid water phantom at isocenter with an instantaneous dose rate of 1.8×105Gy/s and a dose per pulse of up to 1Gy/pulse. Both HEC3 and S4 detectors could record individual pulses for repetition rates of 360Hz with a 4 µs pulse-width. The HEC3 detector signal increased linearly with dose, MU, number of pulses, and dose rate up to 850Gy/s with no loss of functionality at high doses or dose rates. The S4 detector showed linearity with MU and number of pulses at each of the four channels independently showing potential for spatial information and steering but lacked dose rate independence. Two novel detectors, HEC3 and S4, successfully measured electron-FLASH pulses and hence can be considered capable of electron-FLASH beam monitoring in different capacities. HEC3 detector technology is suitable for monitoring high-dose and UHDR beams with high temporal resolution required for pulse counting. We envision the combination of the HEC3 internal structure with the S4 piece-wise design for real-time monitoring of the temporal structure, spatial profiles, energy, and dosimetric properties of UHDR beams.

Optimization of dual-electrode ratio and driving phase of piezoelectric MEMS speakers for improving sound pressure level

The integration of dual-electrode driving to enhance diaphragm deformation, thereby increasing the diaphragm’s average out-of-plane displacement, has proven to be effective in improving the sound pressure level (SPL) of MEMS speakers. In this work, a piezoelectric MEMS speaker with a quasi-enclosed diaphragm and a dual-top electrode (inner and outer) configuration is proposed. With the inner electrode area ideally configured at 70 % of the whole diaphragm, the MEMS speaker with a diaphragm of 2.5 × 2.5 mm2 demonstrates an SPL higher than 73.5 dB in the frequency range from 1 kHz to 20 kHz at a driving voltage of only 2 Vpp. The acoustic performance of the dual-electrode MEMS speaker was also investigated by applying a series of driving signals with different phases and bias voltages to the inner and outer electrodes. It is found that the optimal driving phase varies across different frequency ranges and is dependent on the bias voltage level as well. Moreover, an adequate bias voltage was noted to incrementally enhance the SPL. With proper driving signals optimization, the proposed MEMS speaker achieves an SPL over 88 dB from 100 Hz to 20 kHz at 15 Vpp AC and −2.5 VDC bias voltage. This study furnishes an effective electrode design methodology and driving scheme for the practical deployment of MEMS loudspeakers in future applications.

Effect of thermal annealing on the C(V) characteristic of MSOS structure

In this study, we explore the capacitance C(V) characteristics of metal/polysilicon/silicon oxide/monosilicon (MSPOS) structures. The obtained C(V) curves allow us to analyze the behavior of the capacitance at high frequency as well as the effect of thermal annealing on these characteristics. These reveal particular characteristics of MOS and MOSP structures. The study shows that, under different bias voltages, the obtained curves differ depending on whether the bias is positive or negative. When applying positive voltages, we observe a certain configuration of the curves, while with negative voltages, another configuration appears, always indicating a combination of the C(V) characteristics specific to MOS and MOSP structures. For a substrate doped at a concentration ND = 2.1018 cm-3, we observed a significant variation of the capacitance under the effect of thermal annealing. This thermal treatment, by modifying the crystalline structure of polysilicon, allows the modification of the MOS capacitance. It influences in particular the growth of polysilicon grains as well as the grain boundaries. The results of this study highlight the effect of thermal annealing on polysilicon-based MOS structures. These observations highlight the effect of thermal annealing on the properties of MSPOS structures, by providing a detailed view of how bias voltages and thermal treatment interact to modulate the capacitance characteristics.

On the use of pulsed DC bias for etching high aspect ratio features

Inductively coupled plasmas (ICPs) containing Cl2 are widely used for plasma etching in the semiconductor industry. One common issue during plasma etching is aspect ratio dependent etching (ARDE), which is generally attributed to variation in the flux of etchant species to the bottom of features with different dimensions. Insufficient fluxes of neutral etchants to the bottom of high aspect ratio features can also result in sputtering, which tends to distort the feature profile. This article addresses two issues relevant to Cl2 ICP and plasma etching in these plasmas. First, a comprehensive set of diagnostics is used to validate a model for Cl2 ICP for gas pressure between 3 and 90 mTorr. The plasma diagnostics include microwave resonant hairpin probe-based measurements of electron density, photolysis-calibrated two-photon laser induced fluorescence measurement of Cl density, photo-detachment-based measurement of Cl− density, and laser diode absorption spectroscopy of argon metastable species to measure the gas temperature. Consistent with the experiments, the model shows that the electron density peaks near the center of the chamber at low gas pressure due to rapid diffusion. The electron density peak moves under the coils at higher pressures. Using the validated Cl2 model, we investigate ICPs with rectangular pulsed DC voltage for bias. It is shown that the Cl flux at the bottom of a trench decreases significantly with increasing aspect ratio of the trench. Neutral to ion flux ratio is therefore low at the bottom of higher aspect ratio trenches. The duty cycle of the pulsed bias waveform is found to be an effective means of increasing the neutral to energetic ion flux ratio, which should help with ARDE and sputter reduction.

Silicon-based light-emitting transistor with Ge(Si) nanoislands embedded in a photonic crystal: Control of the spectrum and spatial distribution of the emission

Light-emitting transistors (LETs) represent the next step in the development of light-emitting diodes (LEDs), offering additional control over emission. In this work, the transport properties and spatial distribution of electroluminescence (EL) in the spectral range of 1.2–1.7 μm were studied for lateral p+-i-n+ LEDs based on silicon-on-insulator structures with self-assembled Ge(Si) islands embedded in photonic crystals. It is shown that due to the low mobility of holes and their effective trapping in the islands, the maximum EL yield is observed at the i/p+ junction of the LED. It is demonstrated that the sign and magnitude of the bias voltage applied to the substrate (to the gate) have a significant influence on the transport and emission properties of the LEDs with Ge(Si) islands, turning them into LETs. In particular, applying a negative gate voltage shifts the position of the maximum emission region from the i/p+ to the i/n+ junction of the LET, which is related to the formation of a hole conductivity channel near the buried oxide layer. The embedding of a specially designed photonic crystal in the i-region of the LET makes it possible to manage the spectral properties of the near-IR emission by changing the sign of the gate voltage. The results obtained may be useful for the future development of optoelectronic devices.

Effective spin filter and diode based on triple magnetic junction

The charge current flowing through the triple junction composed of ferromagnetic external electrodes and inner layers of different thickness separated by three non-magnetic barriers is analysed in four colinear magnetic configurations. The thickness of the inner layers and the bias voltage can be set in such a way that the junction can act as a tunnel diode with current flowing effectively in one specific direction. The diode properties of the junction can be adjusted by a change of relative orientation of magnetic moments in the inner layers and electrodes especially the junction can act as a diode in only one magnetic configuration. Magnetic configuration switching can also reverse the direction of the flow of tunnel current.